The split and merge (SAM) protocol for interactive video-on-demand systems

A true video-on-demand (VOD) system provides the ultimate flexibility in video services by allowing users to select any video programs, at any time, and to perform any VCR-like user interactions. To allow true VOD, one approach is to have a dedicated video stream for each customer. This is expensive, especially when multiple identical video streams are sent to multiple customers accessing the same video. To be commercially viable, VOD service must be priced competitively with existing video rental services. Batching may be used to reduce this cost. It allows multiple users accessing the same video to share the same video stream. The batching approach, however, complicates the provision of user interactions. Existing batching schemes only allow near VOD services. This paper describes a new protocol, called split and merge (SAM), which offers true VOD services while allowing multiple users to share the same video stream. This sharing is transparent to the users and it appears as if each has a dedicated video stream. Our approach is to split an interactive user from the batch and to serve him with a dedicated video stream. We develop an innovative way to merge these individuals back to the batching streams when they resume normal play mode. The SAM protocol therefore significantly improves the system resource utilization and the number of simultaneous users, and more importantly, allows true VOD services.